Electric heating unit.



L. F; PARKHU'RST. ELECTRIC asmnc umr. APPLICATION FILED MAR. 28. I916.

PatentedSept. 18,4917.

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Inventor: Leon F Parkhurst by Q l-Iis flttorneg.

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UNITED STATES PATENT OFFICE.

LEON F. PARKHURST, OF PITTSFIELID, MASS ACHUSETTSpASSIGNOR 'IO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTREO HEATING UNIT.

. Specification of Letters Patent. P t t t Application filed March 28, 1916. Serial No. 87,171.

To all whom itmag concern:

Be it known that I, LEON F. PARKHURST, a citizen of the United States, residing at Pittsfield, county of Berkshire, State of Massachusetts, have invented certain new and useful'Improvements in Electric Heating Units, of which the following is a specification.

My invention relates to a heating unit comprising a resistance wire of the type known in the art as sheathed wire and an open metallic frame which supports the heating element-so that it is free to radiate its heat upon the article on which a cooking operation is to be performed, and it has for its object the improvement of a device of this character.

For a fuller understanding of my invention, reference may be had to the accompanying drawings, in which Figure l is a plan yiew of a portion of a heating unit embody- .j ing'my invention, and which is particularly adapted for use as a grill; Fig. 2 is a side view of a portion of Fig. 1; Fig. 3 is a plan View of a portion of a heating unit embodying my invention, which is particularly adapted for use in the oven of an electric range; and Fig. 1 is a sectional side elevation taken on the line 4.--4 of Fig. 3.

Figs. 1 and 2 are the same as Figs. 6 and 7 of a prior application of mine, Ser. No.

l15,097, Electric heating devices, which was filed March 17 1915, and of which the present application is a division in part. I

" have there shown my invention embodied in a grill comprising a metallic supporting frame, including a continuous metal strip 10 and cross metal strips 11, the upper edges of which are bent over at 12 and formed with slots 13in which the sheathed wire 14: is laid, and in which it is locked by rods or bars 15 passing through the reflexed part 12 of the cross strips and over the sheathed wire. Obviously, the refleXed part of the strip may be of any desired length, and may, if desired, be equal in length to the other part of the strip. The sheathed wire is coiled back and forth, and will ordinarily lie in a single plane, and it is apparent that it is held in such a position that it is free to radiate heat transversely to the coils. The

slots or openings for the sheathed wire are alined as shown in Figs. 1 and 3 so that the wire is freely expansible longitudinally as shown, without disturbing the integrity dered material, such as magnesia, which is a a good electrical insulator, but a good conductor of heat. The resistance wire of the sheathed wire 1-1 is connected at 16 to suit able terminal pins 17 which are carried by the metallic supporting frame (only one of tl1es)e connections being shown in the drawmg In Figs. 3 and 4, I have shown my invention embodied in a heating unit particularly suited for use in the oven of an electric range, where it is especially intended for performing baking, broiling, and similar operations. The metal supporting frame comprising the strip 10 and the cross strips 11 is arranged the same as in Figs. 1 and 2, and no detailed description is necessary. The sheathed wire 14: is also arranged in the slots in the cross strips, and locked therein in the same manner as alreadydescribed.

The resistance wires at the ends of the into position on the side brackets in the oven in precisely the same manner as is done with the grid of an ordinary range.

It will be apparent from the foregoing description, that the sheathed wire is supported directly on the metal frame from which the resistance wire is insulated by the layer of insulating material intervening between the resistance wire and the metal sheath, and that the usual insulating members which it is usually found necessary to interpose between the resistance wire and the metallic supporting frame, and which in practice are frequently broken and otherwise injured, are entirely dispensed with. The unit is, in consequence, of a rugged and simple construe tion which is not readily injured by the handlin which in practice it receives.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means.

That I claim as new, and desire to secure by Letters Patent of the United States, is

1. A heating unit comprising a frame pro vided with metal strips formed with openings, metal sheathed insulated resistance wire received Within said openings, and means independent of the metal strips for locking the wire in the openings.

2. A heating unit comprising a frame provided with metal strips formed with openings in their edges, metal sheathed insulated resistance wire laid in said openings, and readily removable means for locking said wire in said openings.

.3. A heating unit comprising a frame pro vided with metal strips formed in their edges with openings, insulated metal sheathed resistance wire laid in said openings, and independent means associated with the metal frame for locking said resistance Wire in said openings.

4. A heating unit comprising a frame hav ing an outer metal strip and metal cross strips secured within the same, said strips being refleXed at their upper edges and formed with slots in the edges of the refiexed portion, insulated resistance wire received within said slots, and rods passing through said outer strip and the reflexed portions of said cross strips and above the resistance wire, for locking the resistance wire to the cross strips.

5. A heating unit comprising a frame provided with metallicstrips forn'fed with a series of alined openings, a metal sheathed insulated resistance wire laid in said openings and freely expansible longitudinally therein, and means for locking the resistance member in said openings.

In witness whereof I have hereunto set my hand this 25th day of March, 1916.

LEON F. PARKHURST. 

